Theodore of Mopsuestia (c. 350–428)

Greek-born Christian bishop, a friend of St John Chrysostom, who converted him to the ascetic life.

Ordained in AD 383, he was a great preacher and scholar, and became bishop of Mopsuestia in Cilicia c. 392. He was a prolific writer, and opposed St Augustine's teaching on original sin. He was attacked after his death for encouraging, by his writing, the heresies of Pelagius and Nestorius, and some of his works were condemned at the fifth synod of Constantinople, in 553, with the reluctant assent later of Pope Vigilius.